High-voltage circuit breaker equipped with hydraulic drive

ABSTRACT

A high-voltage circuit breaker has contacts switchable between open and closed positions and is equipped with a hydraulic actuator operatively connected to the contacts. The actuator is responsive to fluid pressure for switching the contacts. A first fluid supply supplies fluid under low pressure, and a second fluid supply supplies fluid under high pressure. A hydraulic reservoir at ground potential connects the first fluid supply with the second fluid supply for supplying fluid under pressure to the second fluid supply. A valve at high-potential is connected to the hydraulic actuator and includes valve discs for alternately connecting the first fluid supply and the second fluid supply to the hydraulic actuator. The valve discs are controlled from a location at ground potential with the aid of member made of insulating material and are movable between first and second positions. At least one of the valve discs is exposed to the pressure of the fluid of the second fluid supply which places a tension load on the member and acts in a direction to return the discs to the first position.

' United States Patent [191,

Thiirk et al.

HIGH-VOLTAGE CIRCUIT BREAKER EQUIPPED WITH HYDRAULIC DRIVE Inventors: Gerhard Thiirk; Helmut Beier, both of Berlin, Germany Assignee: Siemens Aktiengesellschaft,

Munchen, Germany Filed: May 9, 1973 Appl. No.: 358,829

11.8. C1. 200/82 B, 200/148 F lint. Cl. H0lh 33/34 Field of Search 200/148 E, 148 D, 148 F, 200/148 B, 82 R, 82 B References Cited UNITED STATES PATENTS l/l963 Strom 200/l48 D 3,723,685 3/1973 Thurk 200/148 B 3,745,280 7/1973 Pratsch 200/82 B FOREIGN PATENTS OR APPLICATIONS 1,133,067 11/1968 Great Britain 200/148 E a t a mi 5 I f v [111 3,823,286 [451 July'9,-1974 [57] ABSTRACT A high-voltage circuit breaker has contacts switchable between open and closed positions and is equipped with a hydraulic actuator operatively connected to the contacts. The actuator is responsive to fluid pressure for switching the contacts. A first fluid supply supplies fluid under low pressure, and a second fluid supply supplies fluid under high pressure. A hydraulic reservoir at ground potential connects the first fluid supply with the second fluid supply for supplying fluid under pressure to the second fluid supply. A valve at highpotential is connected to the hydraulic actuator and includes valve discs for alternately connecting the first fluid supply and the second fluid supply to the hydraulic actuator. The valve discs are controlled from a location at ground potential with the aid of member made of insulating material and are movable between first and second positions. At least one of the valve discs is exposed to the pressure of the fluid of the second fluid supply which places a tension load on the member and acts in a direction to return the discs to the first position.

..... .la m 11 D awin i ur M EQUIPPED WITH HYDRAULIC DRIVE BACKGROUND OF THE INVENTION A high-voltage circuit breaker with hydraulic drive is disclosed in Auslegeschrift 1,286,610 wherein the control valve of the hydraulic drive is at high-voltage potential and is located directly next to the drive cylinder in the switching chamber. The control valve is located in a space containing hydraulic fluidlunder low pressure because the space constitutes a part ofa conduit which leads from a fluid collecting vessel at highpotential to the part of the hydraulic system which is at ground potential.

The control valve of the known circuit breaker is a slide valve, because its movable member is a rotatable truncated cone which is providedwith several .bores and can establish different connections between bores in a stationary part against which the truncated cone lies with one of its surfaces. The movable member is operated from a location at ground potential with a member made of insulating material. However, such slide valves are difficult to seal; this results in an undesirably high cost in hydraulic systems which can hardly be compensated for in the known circuit breaker by using the high-pressure line leading to the valve at the same time as a drive member for the rotary motion of the rotatable part of the slide valve.

SUMMARY OF THE INVENTION lt is an object of the invention to improve the seal tightness of an electric circuit breaker equipped with a hydraulic drive so that a simpler configuration is possible. The hydraulic drive includes a control valve which is at high potential and is operated by a member made of insulating material from a location at ground potential. The control valve is located in a space containing hydraulic fluid under low pressure. 'According to a feature of the invention, the valve is configured as a twoway or three-way valve with valve discs acted upon by the pressure medium. An insulating member operates the control valve and is placed under tension by the force exerted by the valve discs and the insulating member is led through a pipe connecting the control valve with a hydraulic fluid reservoir at ground potential.

A high-voltage circuit breaker of the invention can include contacts switchable between open and closed position. Hydraulic actuation means is operatively connected to the contacts and is responsive to fluid pressure for switching the contacts between the open and closed positions. First fluid supply means supplies fluid under low pressure and second fluid supply means supplies fluid under high pressure. Reservoir means at ground potential connects the first fluid supply means with the second fluid supply means for supplying fluid under pressure to the second fluid supply means. A valve at high-potential is connected to the hydraulic actuation meansfThe valve includes cock means movable between first and second positions for alternately connecting the first fluid supply means and the second fluid supply means to the hydraulic actuation means. Control means are also provided and serve to control the cook means from a location at ground potential. The control means is connected'to the cock means for moving the same to the second position thereby connecting the second fluid supply means to the hydraulic actuator. The cock means has surface means exposable to the pressure of the fluid of the second fluid supply means when the same is in the second position thereby placing the control means under a load acting in a direction to return the cock means to the first position.

' According to further feature of the invention, the first fluid supply means includes a container holding the fluid at low pressure. The valve is arranged within the container and defines at least two passages communicating with the hydraulic actuating means. The cock means includes at least two valve discs corresponding to the passages respectively for opening and closing the same. The valve discs are interconnected so as to cause one of the passages to be closed when the other one of the passages is open. One of the valve discs opens the passage corresponding thereto to the first fluid supply means when the cock means is in the first position and the other one of the valve discs opens the passage corresponding thereto to the second fluid supply means when the cock means is in the second position. The control means includes a member made of insulating material connected to the disc valves for moving the same to close the passage to the first fluid supply means and to open the passage to the second fluid supply means. The surface means can be a surface on at least one of the valve discs and is exposed to the pressure of the fluid from the second'fluid supply means when the cock means is in the second position thereby placing the member of the control means under a tensile load acting in a direction to return the cock means to the first position.

The second fluid supply means can .include a'tube conduit connecting the reservoir means to the valve. The member made of insulating material is preferably elongated and is mounted in the tube conduit.

According to still another feature of the invention, the control means further includes'a magnetic drive at ground potential for actuating the elongated member to move the cock means to the second position whereby the fluid of the second fluid supply means acts upon at least one of the valve discs to apply a tension load to the elongated member. Also provided are means for deenergizing the magnetic drive whereby the load acts to return the cock means to the first position. in the high-voltage circuit breaker according to the invention, well-scalable valve discs are provided which can be acted upon by the pressure fluid so that a force results. By means of this force the member made of insulating material which operates the valve is advantageously preloaded in tension. The preloading can be utilized as a driving force for the operation of the valve. Therefore, at least for one direction of motion, a separate drive for the valve can be eliminated.

As mentioned above, the valve discs in the closed position permit the desired excellent seal. At the valve, this sealing is particularly important because these 10- cations are not accessible during the operation of the breaker, and therefore cannot receive maintenance attention. Those parts of the hydraulic drive which are at ground potential, however, can be worked on if necessary even when the breaker carries voltage.

In the breaker according to the invention, the valve is preferably removable from above from the location whereat it is mounted. This simplifies maintenance, so that the down time of the breaker required for repairs is short. It is advantageous to locate the valve below the level of the hydraulic fluid while the sulfur hexafluoride present above the liquid level exerts pressure on the hydraulic fluid by means of a piston. The location of the valve under the hydraulic fluid achieves the result that the hydraulic fluid flowing out of the valve which is displaced by the drive has little or no tendency to develop bubbles or turbulence which could result in gas inclusions in the fluid. For the same purpose, the gas pressure present above the fluid level provides a continuous filling of all pressure medium lines with hydraulic fluid, so that motions of the hydraulic drive can not be delayed by gas bubbles.

Arranging the member for operating the valve in the tube conduit results in a compact configuration with few seals and these are at locations at ground potential. This configuration can be advantageously developed further in that a low-pressure tube surrounds the-tube for the hydraulic fluid under high pressure, the latter enclosing the member made of insulating material. Leakage losses from the high pressure line are then accepted by the low pressure line.

Thus,-according to a subsidiary feature of the invention the first fluid supply means can further include a tubular member surrounding the tube conduit of the second fluid supply means. The tubular member and tube conduit then conjointly define an annular space for connecting the container with the reservoir means. And still another subsidiary feature provides that the reservoir means include a pump, and a hydraulic storage vessel serially connected to the pump. The series circuit of the pump and the hydraulic storage vessel are connected between the annular space and the tube conduit.

Although the invention is illustrated and described herein as a high voltage circuit breaker equipped with a hydraulic drive, it is nevertheless not intended to be limited to the details shown, since various modifications may be made therein within the scope and the range of the claims. The invention, however, together with additional objects andadvantages will be best understood from the following description and in connectionwith the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The drawingillustrates, schematically and partially in section, an elevation view of the high-voltage circuit breaker according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION The high-voltage power circuit breaker is designated with reference numeral 1 and has two switching chambers 2 and 3 which are supported by a metal drive head 4 and are at the same time serially connected. The circuit breaker could be operable, for example, at 220KV. The two switching chambers 2 and 3 are of identical configuration and each contain a stationary contact 6 which engages a movable contact pin 7 when the breaker is in the closed position. The arc resulting when the breaker is switched to the open position is quenched by sulfur hexafluoride which can be, for example, at atmospheres and which fills the interior 8 of the switching chambers. The sulfur hexafluoride can be directed at the arc in a manner known per se by blasting devices (not shown) consisting of pistons and 4 cylinders. The blasting devices and contact pins 7 are actuated by a hydraulic drive 9.

In the illustrated embodiment, a metal container 10 is located within the head 4 from which two cylinders 12 and 13 protrude into the insulators 15 and 16 of the two switching chamber 2 and 3. Drive pistons 19 slide within the cylinders, and are connected to the movable switching pin 7. The pistons 19 are differential pistons, the surfaces 21 of which are smaller than the piston surfaces 22 by the cross sectional area of the switching pin 7 The metal container 10 constitutes a low-pressure container for the hydraulic fluid utilized for actuating the pistons 19, and is at high-voltage potential. A piston 23 rides on top of the fluid and subjects the fluid to the pressure of the sulfur hexafluoride in the breaker which has access via a canal 24. The metal container 10 further contains a combination intake outlet valve designated in its intirety by reference numeral 25; this valve controls the hydraulic actuation. Valve 25 comprisesa movable valve member 26 with a valve disc 27 for the intake side and a valve disc 28 for the outlet side. Both valve discs are connected by means of an insulating rod 29 with a magnetic drive 30 at ground potential. The drive 30 is at ground potential because it is attached to the grounded undercarriage (not shown) of the circuit breaker l. The undercarriage supports the drive head 4 on a hollow support insulator 31.

The insulating rod 29 is located on the axis of the hollow cylindrical .support insulator 31 filled with sulfur 'hexafluoride and consists of glass-fiber reinforced insulating material. The rod 29 extends through a hydraulic high-pressure pipe 32 which is likewise constructed of glass-fiber reinforced laminated material having high mechanical and electric properties.

The pipe 32 made of insulating material is concentrically surrounded by a further pipe 33 also made of insulating material. The insulating pipe 33 consists of a laminated material with an epoxy resin base of high electrical quality and with polyester fibers as reinforcement material. The insulating pipe 33 is resistant to attack by decomposition products of the sulfur hexafluoride so that it does not lose its good electrical properties under the influence of the sulfur hexafluoride.

The annular region 34 between the insulating pipes 32 and 33 serves as a low-pressure hydraulic line through which the low-pressure container 10 is connected with a pump 36 at ground potential. The pump 36 is driven by a motor 37. The pump delivers the hydraulic fluid to the hydraulic reservoir 38 which is also at ground potential and which communicates with the valve 25 at high voltage through the interior 39 of the insulating pipe 32.

The circuit breaker 1 is shown in the open position. To switch the breaker to the closed position, magnet 30 is energized. This causes the valve member 26 to move downwardly. The member 26 closes the outlet to the low-pressure container 10 with valve disc 28. At the same time, the high pressure pipe 32 is connected to the interior 40 of the valve through the opening of the valve disc 27. The high-pressure fluid pushes the pistons 19 away from the valve 25, so that the contact pins 7 come in contact with the stationary contacts 6. This closes the electrical circuit through the breaker which extends through the switching chambers 2 and 3 and the metal drive head 4. The high-pressure fluid on valve disc 28 places the insulating rod 29 under tension. To

switch the breaker to the open position, the insulating rod 29 is controlled in the opposite direction. For this purpose, the magnet 30 is deenergized. The force of the hydraulic fluid present at the valve'disc 28 is sufficient for the operating of the valve 25 provided that the parts of valve member 26 subject to loading are of sufficient size, so that a separate drive is not required. It is important that the large surfaces 22of the differential pistons 19 now are connected with the interior of the low pressure container 10, so that the high-pressure fluid, for example oil, brought by the lines 42 to the smaller piston surfaces 21 can open the circuit breakerll. The top of the container is closed by access means in the form of a cover 44. It is therefore possible to remove and maintain the valve 25 from above without disassembling the breaker.

What is claimed is:

l. A high-voltage circuit breaker comprising contact means switchable between open and closed positions, hydraulic actuation means operatively connected to said contact means and responsive to fluid pressure for switching said contact means between said open and closed positions, first fluid supply means for supplying hydraulic fluid under low pressure, second fluid supply means for'supplying hydraulic fluid under high pressure, hydraulic reservoir means at ground potential connecting said first fluid supply means with said second fluid supply means for supplying fluid under pressure to said second fluid supply means, a valve at highpotential connected to said hydraulic actuation means, said valve including cock means-movable between first and second positions for alternately connecting said first fluid supply means and said second fluid supply means to said hydraulic actuation means, and control means for controlling said cock means from a location at ground potential, said control means connected to said cock means for moving thesame to said second position thereby connecting said second fluid supply means to said hydraulic actuation means, said cock means having surface means exposable to the pressure of the fluid of said second fluid supply means when the same is in said second position thereby placing said control means under a load acting in a direction to return said cock means to said first position.

2. The high-voltage circuit breaker of claim ll, said first fluid supply means comprising a container holding fluid at low pressure, said valve being arranged within said container and defining at least two passages communicating with said hydraulic actuating means, said cock means comprising at least two valve discs corresponding to said passages respectively for opening and closing the same, said valve discs being interconnected so as to cause one of said passages be closed when the other one of said passages is open, one of said valve discs opening the passage corresponding thereto to said first fluid supply means when said cock means is in said first position, the other one of said valve discs opening the passage corresponding thereto to said second fluid supply means when said cock means is in said second position, said control means comprising a member made of insulating material connected to said disc valves for moving the same to close the passage to said first fluid supply means and to open the passage to said second fluid supply means, and said surface means being a surface on at least one of said valve discs and being exposed to the pressure of the fluid from said second fluid supply means when said cock means is in said second position thereby placing said member of said control means under a tensile load acting in a direction to returnsaid cock means to said first position.

3. The high-voltage circuit breaker of claim 2, said I second fluid supply means comprising a tube conduit connecting said hydraulic reservoir means to said valve, said member made of insulating material being elongated and being arranged in said tube conduit.

4. The high-voltage circuit breaker of claim 3, said control means furthercomprising a magnetic drive at ground potential for actuating said elongated member to move said cock means to said second position whereby the fluid of said second fluid supply means acts upon at least one of said disc valves to apply a tension load to said member, and means for deenergizing said magnetic drive whereby said loa'd acts to return said cock means to said first position.

5. The high-voltage circuit breaker of claim 3 comprising access means disposed over said container for rendering said valve accessible and removable from above.

6. The high-voltage circuit breaker of claim 3 comprising a housing surrounding said container, contact means and hydraulic actuator means, said housing being fillable with a quenching gas such as sulfur hexafluoride or the like, said valve being disposed at an elevation below the level of the fluid, and a piston arranged at said container forapplying a pressure to the fluid in response to the pressure applied to said piston by the gas.

7. The high-voltage circuit breaker of claim 3, said first fluid supply means comprising a tubular member surrounding said tube conduit and conjointly defining therewith an annular space for connecting said container with said reservoir means.

h. The high-voltage circuit breaker of claim 7, said reservoir means comprising a pump, and a hydraulic storage vessel serially connected to said pump, the series circuit of said pump and said hydraulic storage vessel being connected between said annular space and 

1. A high-voltage circuit breaker comprising contact means switchable between open and closed positions, hydraulic actuation means operatively connected to said contact means and responsive to fluid pressure for switching said contact means between said open and closed positions, first fluid supply means for supplying hydraulic fluid under low pressure, second fluid supply means for supplying hydraulic fluid under high pressure, hydraulic reservoir means at ground potential connecting said first fluid supply means with said second fluid supply means for supplying fluid under pressure to said second fluid supply means, a valve at high-potential connected to said hydraulic actuation means, said valve including cock means movable between first and second positions for alternately connecting said first fluid supply means and said second fluid supply means to said hydraulic actuation means, and control means for controlling said cock means from a location at ground potential, said control means connected to said cock means for moving the same to said second position thereby connecting said second fluid supply means to said hydraulic actuation means, said cock means having surface means exposable to the pressure of the fluid of said second fluid supply means when the same is in said second position thereby placing said control means under a load acting in a direction to return said cock means to said first position.
 2. The high-voltage circuit breaker of claim 1, said first fluid supply means comprising a container holding fluid at low pressure, said valve being arranged within said container and defining at least two passages communicating with said hydraulic actuating means, said cock means comprising at least two valve discs corresponding to said passages respectively for opening and closing the same, said valve discs being interconnected so as to cause one of said passages be closed when the other one of said passages is open, one of said valve discs opening the passage corresponding thereto to said first fluid supply means when said cock means is in said first position, the other one of said valve discs opening the passage corresponding thereto to said second fluid supply means when said cock means is in said second position, said control means comprising a member made of insulating material connected to said disc valves for moving the same to close the passage to said first fluid supply means and to open the passage to said second fluid supply means, and said surface means being a surface on at least one of said valve discs and being exposed to the pressure of the fluid from said second fluid supply means when said cock means is in said second position thereby placing said member of said control means under a tensile load acting in a direction to return said cock means to said first position.
 3. The high-voltage circuit breaker of claim 2, said second fluid supply means comprising a tube conduit connecting said hydraulic reservoir means to said valve, said member made of insulating material being elongated and being arranged in said tube conduit.
 4. The high-voltage circuit breaker of claim 3, said control means further comprising a magnetic drive at ground potential for actuating said elongated member to move said cock means to said second position whereby the fluid of said second fluid supply means acts upon at least one of said disc valves to apply a tension load to said member, and means for deenergizing said magnetic drive whereby said load acts to return said cock means to said first position.
 5. The high-voltage circuit breaker of claim 3 comprising access means disposed over said container for rendering said valve accessible and removable from above.
 6. The high-voltage circuit breaker of claim 3 comprising a housing surrounding said container, contact means and hydraulic actuator means, said housing being fillAble with a quenching gas such as sulfur hexafluoride or the like, said valve being disposed at an elevation below the level of the fluid, and a piston arranged at said container for applying a pressure to the fluid in response to the pressure applied to said piston by the gas.
 7. The high-voltage circuit breaker of claim 3, said first fluid supply means comprising a tubular member surrounding said tube conduit and conjointly defining therewith an annular space for connecting said container with said reservoir means.
 8. The high-voltage circuit breaker of claim 7, said reservoir means comprising a pump, and a hydraulic storage vessel serially connected to said pump, the series circuit of said pump and said hydraulic storage vessel being connected between said annular space and said tube conduit. 